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Questions and Answers
What does Mendel refer to as a heritable feature that differs among individuals?
What does Mendel refer to as a heritable feature that differs among individuals?
- Character (correct)
- Trait
- Generation
- Hybrid
What is the name of the process Mendel used to produce hybrid offspring?
What is the name of the process Mendel used to produce hybrid offspring?
- Hybridization (correct)
- Segregation
- Self-fertilization
- Cross-pollination
Which generation is produced from the cross of two true-breeding varieties?
Which generation is produced from the cross of two true-breeding varieties?
- F2 generation
- P generation
- Hybrid generation
- F1 generation (correct)
What happened when Mendel cross-pollinated white flowered and purple flowered pea plants?
What happened when Mendel cross-pollinated white flowered and purple flowered pea plants?
Which of the following principles of heredity did Mendel deduce from his experiments?
Which of the following principles of heredity did Mendel deduce from his experiments?
Why did Mendel choose pea plants for his experiments?
Why did Mendel choose pea plants for his experiments?
What was the result of Mendel's expectation if blending model of inheritance were true?
What was the result of Mendel's expectation if blending model of inheritance were true?
What character did Mendel track in his pea plant experiments?
What character did Mendel track in his pea plant experiments?
What determines the ABO blood groups in humans?
What determines the ABO blood groups in humans?
Which of the following best describes pleiotropy?
Which of the following best describes pleiotropy?
What is the phenotypic outcome when two heterozygous individuals are crossed in a polygenic trait like skin color?
What is the phenotypic outcome when two heterozygous individuals are crossed in a polygenic trait like skin color?
Which statement correctly describes epistasis?
Which statement correctly describes epistasis?
How many genetic variations influence human height?
How many genetic variations influence human height?
Which of the following traits is an example of polygenic inheritance?
Which of the following traits is an example of polygenic inheritance?
What does the term 'multifactorial' refer to in genetics?
What does the term 'multifactorial' refer to in genetics?
What characterizes a phenotype?
What characterizes a phenotype?
What type of genetic relationship does polygenic inheritance represent?
What type of genetic relationship does polygenic inheritance represent?
Which statement regarding environmental factors in multifactorial characters is true?
Which statement regarding environmental factors in multifactorial characters is true?
What is the purpose of a testcross?
What is the purpose of a testcross?
What type of offspring results from a cross between two true-breeding plants with different traits for a single character?
What type of offspring results from a cross between two true-breeding plants with different traits for a single character?
What are the expected phenotypic ratios resulting from a dihybrid cross under the Law of Independent Assortment?
What are the expected phenotypic ratios resulting from a dihybrid cross under the Law of Independent Assortment?
Which hypothesis predicts the alleles for different characters assort together during gamete formation?
Which hypothesis predicts the alleles for different characters assort together during gamete formation?
In Mendel's experiments, which generation was produced by self-pollinating dihybrid F1 plants?
In Mendel's experiments, which generation was produced by self-pollinating dihybrid F1 plants?
What does the multiplication rule in genetics help determine?
What does the multiplication rule in genetics help determine?
What genotype would result from a testcross involving a heterozygous individual?
What genotype would result from a testcross involving a heterozygous individual?
What would Mendel's testcross reveal about the genotype of a plant with purple flowers?
What would Mendel's testcross reveal about the genotype of a plant with purple flowers?
Which statement reflects Mendel's Law of Independent Assortment?
Which statement reflects Mendel's Law of Independent Assortment?
Which gametes can a plant with genotype YyRr produce under independent assortment?
Which gametes can a plant with genotype YyRr produce under independent assortment?
What would be the outcome if alleles assort dependently?
What would be the outcome if alleles assort dependently?
Why do plants with genotype YyRr exhibit dominant traits?
Why do plants with genotype YyRr exhibit dominant traits?
In Mendel's dihybrid crosses, what pattern did he observe among the phenotypic ratios?
In Mendel's dihybrid crosses, what pattern did he observe among the phenotypic ratios?
What is the primary evidence that the white-flower trait reappears in the F2 generation?
What is the primary evidence that the white-flower trait reappears in the F2 generation?
What are alleles in the context of Mendel's experiments?
What are alleles in the context of Mendel's experiments?
According to Mendel's Law of Segregation, what occurs during gamete formation?
According to Mendel's Law of Segregation, what occurs during gamete formation?
In Mendel's F1 hybrids, which genotype would result in a purple flower trait?
In Mendel's F1 hybrids, which genotype would result in a purple flower trait?
What is a testcross used for in genetics?
What is a testcross used for in genetics?
What type of genotype is represented by a plant that is homozygous for a trait?
What type of genotype is represented by a plant that is homozygous for a trait?
What was the approximate phenotypic ratio of purple to white flowers in Mendel's F2 generation?
What was the approximate phenotypic ratio of purple to white flowers in Mendel's F2 generation?
Which of the following best describes a heterozygote?
Which of the following best describes a heterozygote?
In Mendel's experiments, which statement is true about the F1 generation?
In Mendel's experiments, which statement is true about the F1 generation?
What role do chromosomes play in Mendel's model of inheritance?
What role do chromosomes play in Mendel's model of inheritance?
What happens if a pink flower trait was observed alongside purple and white flowers in offspring?
What happens if a pink flower trait was observed alongside purple and white flowers in offspring?
Which statement accurately reflects Mendel’s view of dominant and recessive traits?
Which statement accurately reflects Mendel’s view of dominant and recessive traits?
Which of the following concepts did Mendel not consider when developing his model?
Which of the following concepts did Mendel not consider when developing his model?
If a homozygous dominant plant (PP) is crossed with a heterozygous plant (Pp), what is the expected phenotypic ratio of their offspring?
If a homozygous dominant plant (PP) is crossed with a heterozygous plant (Pp), what is the expected phenotypic ratio of their offspring?
What is the overall probability of obtaining an Rr heterozygote from a monohybrid cross?
What is the overall probability of obtaining an Rr heterozygote from a monohybrid cross?
Which rule is used to calculate the probability of multiple independent genetic events, like obtaining genotypes from a dihybrid cross?
Which rule is used to calculate the probability of multiple independent genetic events, like obtaining genotypes from a dihybrid cross?
How can at least two recessive phenotypes be expected in offspring from a cross involving three characters?
How can at least two recessive phenotypes be expected in offspring from a cross involving three characters?
What is the expected phenotype ratio for the recessive trait of seed color (yy) from a cross between Yy and yy parents?
What is the expected phenotype ratio for the recessive trait of seed color (yy) from a cross between Yy and yy parents?
How does incomplete dominance differ from complete dominance in genetic expression?
How does incomplete dominance differ from complete dominance in genetic expression?
Which scenario exemplifies codominance?
Which scenario exemplifies codominance?
How many different combinations of recessive traits can appear from the PpYyRr x Ppyyrr cross?
How many different combinations of recessive traits can appear from the PpYyRr x Ppyyrr cross?
In Mendel's pea plants, what is the main reason that the F1 hybrids appear indistinguishable from the dominant homozygotes?
In Mendel's pea plants, what is the main reason that the F1 hybrids appear indistinguishable from the dominant homozygotes?
What probability is assigned to a dominant homozygote offspring phenotype resulting from a monohybrid cross?
What probability is assigned to a dominant homozygote offspring phenotype resulting from a monohybrid cross?
What outcome occurs when a recessive allele and a dominant allele coexist in a heterozygote?
What outcome occurs when a recessive allele and a dominant allele coexist in a heterozygote?
In calculating the probabilities for multiple traits, what mathematical operation is indicated by the term 'and'?
In calculating the probabilities for multiple traits, what mathematical operation is indicated by the term 'and'?
From the PpYyRr x Ppyyrr cross, what fraction of offspring is expected to exhibit the dominant phenotypes for all three traits?
From the PpYyRr x Ppyyrr cross, what fraction of offspring is expected to exhibit the dominant phenotypes for all three traits?
Which of the following statements about Mendelian classifications of dominance is true?
Which of the following statements about Mendelian classifications of dominance is true?
For a single gene with two alleles, what term describes when both alleles contribute equally to the phenotype in heterozygotes?
For a single gene with two alleles, what term describes when both alleles contribute equally to the phenotype in heterozygotes?
Flashcards
Mendel's experimental approach
Mendel's experimental approach
Mendel used controlled matings of pea plants to study patterns of inheritance.
Character
Character
Heritable feature differing among individuals; Ex: flower color.
Trait
Trait
Variants of a character; Ex: purple or white flower color.
Cross-pollination
Cross-pollination
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P generation
P generation
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F1 generation
F1 generation
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Law of Segregation
Law of Segregation
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Hybrid offspring
Hybrid offspring
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Dominant allele
Dominant allele
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Recessive allele
Recessive allele
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Allele
Allele
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Homozygote
Homozygote
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Heterozygote
Heterozygote
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Phenotype
Phenotype
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Genotype
Genotype
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Testcross
Testcross
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True-breeding
True-breeding
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3:1 ratio
3:1 ratio
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Monohybrid cross
Monohybrid cross
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Locus
Locus
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Diploid
Diploid
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What is a dihybrid cross?
What is a dihybrid cross?
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Independent Assortment
Independent Assortment
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Phenotypic ratio
Phenotypic ratio
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What is the phenotypic ratio of a dihybrid cross?
What is the phenotypic ratio of a dihybrid cross?
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Multiplication rule
Multiplication rule
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What is the difference between dependent and independent assortment?
What is the difference between dependent and independent assortment?
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What does a 3:1 phenotypic ratio indicate?
What does a 3:1 phenotypic ratio indicate?
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What are the possible gametes produced by a YyRr plant?
What are the possible gametes produced by a YyRr plant?
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What does the 9:3:3:1 phenotypic ratio of a dihybrid cross demonstrate?
What does the 9:3:3:1 phenotypic ratio of a dihybrid cross demonstrate?
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How does the Law of Independent Assortment apply to chromosomes?
How does the Law of Independent Assortment apply to chromosomes?
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What are the key observations from Mendel's dihybrid cross experiments?
What are the key observations from Mendel's dihybrid cross experiments?
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How can we apply the multiplication rule to monohybrid crosses?
How can we apply the multiplication rule to monohybrid crosses?
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Addition Rule
Addition Rule
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Dihybrid cross
Dihybrid cross
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Incomplete Dominance
Incomplete Dominance
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Codominance
Codominance
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Recessive phenotype
Recessive phenotype
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Dominant phenotype
Dominant phenotype
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Probability of Recessive Phenotypes
Probability of Recessive Phenotypes
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What is the key difference between incomplete dominance and codominance?
What is the key difference between incomplete dominance and codominance?
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Why is an allele considered 'dominant'?
Why is an allele considered 'dominant'?
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How does the defective enzyme in the wrinkled pea seed allele affect phenotype?
How does the defective enzyme in the wrinkled pea seed allele affect phenotype?
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Explain why a heterozygous individual with a dominant allele doesn't necessarily express the recessive trait.
Explain why a heterozygous individual with a dominant allele doesn't necessarily express the recessive trait.
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Can you predict the genotypic ratio of an F2 generation from a dihybrid cross?
Can you predict the genotypic ratio of an F2 generation from a dihybrid cross?
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Multiple Alleles
Multiple Alleles
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Pleiotropy
Pleiotropy
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Epistasis
Epistasis
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Quantitative Characters
Quantitative Characters
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Polygenic Inheritance
Polygenic Inheritance
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Multifactorial
Multifactorial
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Blood Transfusion
Blood Transfusion
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Study Notes
Mendel's Experimental Approach
- Mendel likely chose pea plants due to their availability in various traits (e.g., purple or white flowers).
- A character is a heritable feature that varies among individuals, and a trait is a specific variant of that feature.
- Pea flowers allow for self-fertilization or controlled cross-pollination by removing stamens and transferring pollen.
- Mendel tracked traits across generations (P, F1, F2) using large sample sizes and precise records.
- He focused on characters with distinct, alternative forms.
The Law of Segregation
- If inheritance were blending, F1 offspring would show an intermediate trait, but all F1 offspring had the same color (purple) as one parent.
- Mendel's data showed a 3:1 ratio of purple to white flowers in the F2 generation, demonstrating that traits, not diluted, were passed on.
- Purple is the dominant trait, white is recessive—the recessive trait reappeared in the F2 generation.
- Mendel's model explains the 3:1 pattern:
- Alternate versions of genes (alleles) cause variations in a character.
- Each organism has two alleles for each character—one from each parent (diploid).
- If alleles differ, the dominant allele determines the appearance, and the recessive has no effect.
- Alleles segregate during gamete formation. This relates to the distribution of chromosomes in meiosis.
Useful Genetic Vocabulary
- Homozygote: organism with identical alleles for a gene (e.g., PP or pp)
- Heterozygote: organism with different alleles for a gene (e.g., Pp)
- Genotype: genetic makeup
- Phenotype: observable traits
The Testcross
- Used to determine an unknown genotype of an organism showing a dominant trait.
- Involves crossing the unknown with a homozygous recessive individual.
The Law of Independent Assortment
- Mendel extended his studies to two characters simultaneously, like seed color and shape.
- Dihybrid crosses (YyRr x YyRr) revealed that alleles for different genes segregate independently into gametes.
- Independent assortment results in a 9:3:3:1 phenotypic ratio in the F2 generation. This differs from a 3:1 ratio in monohybrid crosses.
Probability and Mendelian Inheritance
- The multiplication rule determines the probability of independent events occurring together (e.g., two heads from two coin flips = 1/4).
- The addition rule determines the probability of any one of multiple mutually exclusive events occurring.
- These rules are applied to solve more complex crosses.
Extending Mendelian Genetics
-
Degrees of Dominance:
- Complete dominance: one allele fully masks the other (Mendel's peas).
- Incomplete dominance: heterozygotes have an intermediate phenotype (e.g., pink snapdragons).
- Codominance: both alleles are fully expressed in heterozygotes (e.g., MN blood groups)
-
Multiple alleles: more than two alleles for a gene exist (e.g., ABO blood groups)
-
Pleiotropy: one gene influences multiple traits (e.g., sickle cell disease).
-
Epistasis: one gene affects the expression of another.
-
Polygenic inheritance: multiple genes additively influence a trait (e.g., human skin color)
Environmental Impact
- Environment often influences the phenotype of polygenic traits (multifactorial inheritance).
- Genotype does not fully determine the phenotype; environment plays a role.
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Description
Explore Mendel's revolutionary experiments with pea plants that led to foundational principles in genetics. This quiz covers his experimental approach, the concept of inheritance, and the Law of Segregation. Test your knowledge on the characteristics and traits Mendel meticulously tracked across generations.
